For console I have to use the swimming pool to kill them by drowning which is used when they get murdered by evil sim, suicide, dying to food poisoning, hit by car (car driving through sim when they cross road) and dying while giving birth (when mature), for PC/mac edition; I use mods. Mods makes activating deaths a lot easier. :D
Kinda wished that the devs added death cheats for vanilla using social interaction wheel when cheats are on, kinda like how they can when they are in admin mode, but whatever.